You can look into the kitty litter background as well. I will never again do a great stuff background. Lots cheaper.
At first I was wondering why you wanted to squeeze a waterfall in that 10 gallon but then I remembered that I learned how to read in elementary school. You can always do away with that if you want the extra room. I siphon mine with a little airline tubing and it is not a monthly affair.
They don't really need ventilation unless you are soaking the substrate, then it's a husbandry issue. I leave a little gap in the tank lid.
I promise that you are going to want to get them into a larger tank in 6 months. I would have each of my tinc pairs in a 55 gallon if I had the space.
Love the Matechos.
Please get comfortable with making fruit fly cultures before your frogs come. There is nothing worse than not having anything to feed them after a culture crash.